This invention relates to a transmission mechanism for a marine outboard drive and more particularly to an improved supporting and driving arrangement for the propeller shaft of such a drive.
As is well known most marine outboard drives, be they the lower unit of an outboard motor or the lower unit of the outboard drive portion of an inboard/outboard drive assembly, have a drive shaft and propeller shaft that extend at right angles to each other. Some form of driving mechanism, normally a forward, neutral, reverse transmission interconnect the drive shaft and the propeller shaft for driving the propeller shaft. The rear end of the propeller shaft extends through an opening in the rear face of the lower unit and a propeller is affixed to the extending end of the propeller shaft. With such arrangements, the rear or trailing end of the propeller shaft is supported by means of an anti-friction bearing. However, the inner end of the propeller shaft is not normally directly supported by an anti-friction bearing and, hence, the propeller shaft is cantilevered about the rearwardly positioned bearing. Such cantilevered support for the propeller shafts can cause wear and other problems in connection with the transmission of power.
It is, therefore, a principal object of this invention to provide an improved bearing arrangement for the propeller shaft of a marine outboard drive.
It is a further object of this invention to provide a bearing arrangement for a marine drive propeller shaft wherein the propeller shaft is supported by spaced apart bearings so as to avoid cantilever loading and twisting forces.
In marine outboard drive transmissions, it is frequently necessary or desirable to provide a splined connection between the propeller shaft and a further driving shaft of the transmission. When such a splined connection is employed, good support should be provided for the splined portions of the shaft so as to insure against bending loads, as might be resultant if a cantilevered construction is provided. In addition, it is desirable to provide the splined connection in such a way that a relatively large and robust bearing may be provided.
It is, therefore, a further object of this invention to provide an improved bearing arrangement for a splined propeller shaft drive of a marine outboard unit.